PLATE AS-HINGE 4265175 - Caterpillar

Apron Sequence Relief Valve
When the apron circuit is in HOLD position and the apron is forced upward by an obstruction or by raising the bowl with the apron closed, the apron sequence relief valve (21) functions as a relief valve.
APRON SEQUENCE RELIEF VALVE SCHEMATIC
38. Shims. 39. Port to head end of apron cylinder. 40. Relief valve. 41. Port to rod end of apron cylinder.When the pressure of the oil in the rod end of the cylinder reaches the relief valve setting, the pressure forces the valve (40) against the force of its spring, opening port (39) to port (41). The rod end oil is then directed to the head end of the cylinder, allowing the apron to be raised.Adding shims (38) increases the relief valve setting; removing shims decreases the setting.Ejector Control-Later Machines
Eject
In EJECT position the control valve (19) is moved inward. Pump oil flows to the head end of the ejector cylinder, moving the ejector forward. The oil in the rod end of the cylinder returns to the tank through the common line (18).Return (flow control)
In RETURN (flow control) position the valve spool (19) is moved outward. The ejector spool is held in RETURN position by detents.Pump oil is restricted by the position of the valve spool (19). Some oil is dumped to the tank by the relief valve (2) which acts as a flow control valve in RETURN (flow control) position. The remainder of the oil flows to the common line (18) to the rod end of the ejector cylinder. A detailed description of the relief valve (2) is discussed later.When the ejector is completely retracted, pressure increases in the common passage and is sensed on piston (14). When the pressure reaches the kickout pressure, the piston returns the valve spool to HOLD position.Return (override)
The control valve spool is moved further out of the body. Pump flow is not restricted by the valve spool and full pump flow is directed to the rod end of the cylinder, increasing the return speed of the ejector.
EJECTOR CYLINDER
16. Line (control valve-to-head end of ejector cylinder). 23. Line to rod end of ejector cylinder. 24. Ejector cylinder.Ejector Control-Early Machines
Eject
In EJECT position the control valve spool (19) is moved inward. Pump oil flows to the head end of the ejector cylinder (24), moving the ejector forward. The oil in the rod end of the ejector cylinder returns through line (18).Return
When the control valve spool (19) is moved outward for ejector RETURN, pressure oil is directed from the control valve, through lines (18) and (23) to the rod end of the ejector cylinder (24). Oil from the head end of the ejector cylinder returns to the control valve and to the tank through line (16).Control valve spool (19) has a hydraulic lockout in the RETURN position when the ejector cylinder rod is retracting. The pressure of the return oil is sensed in the cavity at the right end of spool (19). Oil pressure in the cavity holds the spool in the RETURN